class Car:
    """一次模拟汽车的简单尝试"""

    def __init__(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year
        self.odometer_reading = 0

    def get_descriptive_name(self):
        long_name = f"{self.year} {self.make} {self.model}"
        return long_name.title()

    def read_odometer(self):
        print(f"This car has {self.odometer_reading} miles on it.")

    def update_odometer(self, mileage):
        if mileage >= self.odometer_reading:
            self.odometer_reading = mileage
        else:
            print("You can't roll back an odometer.")

    def increment_odometer(self, miles):
        self.odometer_reading += miles


class ElectricCar(Car):
    """电动汽车的独特之处"""

    def __init__(self, make, model, year):
        """初始化父类的属性"""
        super().__init__(make, model, year)
        """再初始化电动车特有的属性"""
        self.battery_size = 75

    def describe_battery(self):
        print(f"This car has a {self.battery_size}--kWh battery.")

# 为了演示导入类，先注释掉下面部分
# my_tesla = ElectricCar("tesla", "model s", 2019)
# print(my_tesla.get_descriptive_name())
# my_tesla.describe_battery()
